Re: [MedievalSawdust] Re: Vice screws ? (update)

It takes a lot of work to make a good tool, the better the tool the more work. I have a conflicting and duel line of thought on making tools and caring for

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, Dec 30, 2012

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It takes a lot of work
to
make a good tool, the better the tool the more work. I have a
conflicting and duel line of thought on making tools and caring
for
tools. Tools should be appropriately respected and cared for. On
the other hand, tools, all, tools, are disposable implements
that are
designed to make something else. Heat treatment of metal tools
even
today with modern alloys and furnaces that can be set for exact
temperatures is still an art. What is good for one tool and tool
application is not the best for another, and the perfect process
for
one tool and application may may need to be changed when the
size of
tool is the only variable that has changed. My point is don't
get
too caught up in heat treatment processes. A mild steel
un-heat-treated blade in your screw-cutter may need to be honed
more
often, maybe even several times before one screw is finished but
is
much much easier to shape and can be done very precisely with
hand
files and then finished by honing. I am guessing that your
planing
on making a hand full of wooden screws, not several thousand. If
that's the case making the blades of a high quality shape in a
poorer
quality metal will get the job done better that a poorly shaped
m2
blade that you have ground on for hours with a small hand
grinder
which admittedly may last you nearly forever in all its poor
quality
grandeur. As both a woodworker and a smith I will say that all
can
be done with the right materials and a little practice.
Annealing a
carbon steel make it soft (so you can file it) heating and
quenching
makes it hard and brittle (so it will hold an edge longer) and
tempering removes brittleness (so your tool doesn't brake like
glass
when you drop, strike, or hit something unexpectedly with it).
If
learning these skills are on your back burner instead of your
back
pocket then don't let that get in the way of your making a good
tool
to do the job you are doing. The job of your tool is to teach
you
how the tools to thread nuts and rods were made and then to make
a
few. It doesn't need to last forever.

I am very interested in
screws (and medieval threaded fasteners in general and not just
wood
ones) and would like to see your documentation for the threading
devices you mentioned. I have a picture of Hero's but it is
confusing, and is a drawing not from a primary source.

I got two "sample" turning blanks (3" square by
a 12") one was hard maple, the other sycamore
(it was cheaper for some reason). My plan to
was to practice before cutting a large maple
one.

I chiseled away at about 2 inches of thread on
the hard maple blank, about 6 turns into the
nut. The manually cut threads are pretty close
to the right patch. My major diameter was too
thick so that caused me to thing I had the wrong
pitch.

My screwbox cutter is the wrong shape and not
sharp enough, so I decided to abandon that part
of the project for now. A two and a half inch
major diameter screw needs two cutters. I'm not
sure I'm smart enough to get that to work.

I took a short cut, a bit strange because I'm
mostly a hand tool using primate. The chiseling
was just too slow.

I mounted the screwbox on the mini-mill, chucked
up a 60 degree 1/2" router bit, lined it up
where the cutter should have been and manually
turned the screw into the screwbox past the
router bit. Other that some chewed up threads,
that look a lot like the ones I did with a
chisel they threads came out pretty decent. The
will not win a beauty contest, but they are
strong and hold fast. I'd like to state this
process is NOT for the faint of heart, even with
everything mounts securely to the table there is
lots of vibration and chips flying everywhere.

The hard maple one threads are a little smoother
than the sycamore. Since the maple was the one
I did first, likely if I did another one it
would come out better.

One thing that I did note is that you can't find
a large triangular file at a home store or
Menard's. So I'll be making a triangular
sanding block so that I can smooth out the
tooling marks and make things work a little
better.

I have a Moxon vise that I make with the 6
threads/inch 1.5" screws that I have not been
happy with so I decided to drill out the holes
and tap them with the new manual tap since I
have two fully functional screws. So far that
process has gone pretty well.

I'll try and get some pictures eventually of the
results.

I'll send another update in a couple of days.

Peter

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